The treatment of early stage, localized breast cancer has evolved over several decades from highly invasive techniques to minimally invasive, breast-conserving therapies. Our breast-specific magnetic resonance-guided focused ultrasound system ? the ?Muse? MRgFUS System ? non-invasively delivers focused energy deep inside the body under high-resolution image guidance. The technical advances we have made poise MRgFUS as a nearly ready non-invasive ablation treatment for localized breast disease. The final steps for its clinical translation include studies to compare, optimize and carefully validate treatment planning, real-time monitoring and assessment techniques against the best available standard metrics, which include invasive temperature probes, hydrophone measurements and histopathology. This proposal pairs experienced academic investigators at the University of Utah with industry investigators at Image Guided Therapy. Combining the academic partner's scientific expertise and technological knowledge with the system integration and regulatory expertise of the industry partner will facilitate translation of this exciting technology. This proposal will develop and validate the remaining elements necessary to translate the Muse System into clinical care including: 1) accurate MRgFUS treatment planning based on a rapid ultrasound beam modeling method, 2) a comprehensive breast-focused volumetric MR thermometry method, and 3) a novel MRI-registered whole mount histology technique that compares MRI metrics to histopathological analysis. We will integrate each of these validated elements in a clinic-ready, treatment software control environment and will evaluate the entire process in a Phase I treat-and-resect clinical trial targeting unifocal invasive breast cancer tumors. The validation and translation of the Muse System in this proposal will provide an exciting new image-guided non- invasive treatment option for breast cancer patients.